Conventional vehicle powertrains are equipped with thermal management systems to control the temperature of powertrain components during vehicle operation. For example, vehicles commonly have a radiator in thermal communication with the engine to remove heat therefrom. There are also heat exchangers that warm and/or cool automatic transmission fluid when needed. It is desirable to have a multiple zone radiator with various temperature zones configured to separately cater to the thermal demands of different powertrain components (e.g., one zone for the engine and another zone for automatic transmission fluid).
U.S. Pat. No. 7,464,781 to Guay et al. titled “Three-Wheeled Vehicle Having a Split Radiator and an Interior Storage Compartment” presents the use of two separate radiators to accommodate vehicle packaging restraints. The '781 patent teaches that the radiators can be arranged in series or in parallel. However, the radiators are housed in different locations and said radiators appear to be dedicated to engine oil cooling only.
It is more beneficial to have a single radiator with designated sections or zones for different cooling temperatures. A single radiator unit generally requires less parts, assembly time and packaging space and would result in less weight for the vehicle. The utilization of a single radiator can also yield significant undesirable results. For example, the temperature differential between zones can cause unwanted structural strain on the radiator housing. Commonly, when coolant is flowing through one zone but not flowing in an adjacent zone the radiator housing can be subject to unwanted strain. Radiator channels can thermally expand at a higher rate in zones where coolant is flowing than the channels without coolant flowing.
One solution available in the automotive industry is the use of an aperture (or orifice) in a baffle which divides zones of the radiator. The presence of the orifice allows flow from one zone to another whenever the zone is flowing while the other zone otherwise would not. This solution may reduce thermal strain but also reduces the cooling benefits of a multiple zone radiator with lower temperature zone. The zone intended to run colder tends to leak into the adjacent zone, which has the tendency of increasing its temperature as well as reducing flow intended for a downstream heat exchanger. Therefore, it is desirable to have a multiple zone vehicle radiator that reduces unwanted strains on the radiator housing during operation without compromising outlet temperature and flow to downstream heat exchangers.